This invention pertains to the art of valves and, more particularly, to drain valves. The invention is particularly applicable to a drain valve for use with a water heater or an on/off valve in a related environment and will be described with particular reference thereto. However, it will be appreciated that the invention has broader applications and may be advantageously employed in other fluid control environments.
Prior art on/off valves used to drain a water heater or similar appliances have suffered from various drawbacks. The infrequent use of valves of this type requires a durable, reliable sealing structure that is unaffected by extended periods of non-use and the corrosive effects of the system fluid. One particular drawback is the structural complexity of the valves requiring close tolerances which are expensive to machine. The intricate passageways, valve assemblies, valve seats, and seals are subject to wear over time or are constructed of metallic materials which are subject to corrosion. Due to infrequent use of the drain valves in such an environment, various operative components of the valve have frozen or fused together requiring drastic, or even destructive, action to obtain valve opening.
Later developments in valves of this general type have utilized non-metallic materials in an effort to overcome the corrosion problems. Various types of plastic or other non-metallic valves have been developed, all with associated production difficulties, excessive costs, and performance problems. For example, some plastics are unable to withstand the high pressures associated with the pressure head and were subjected to deflection or deformation. This eventually led to improper sealing or difficulty in operating the valve. Still other prior designs lacked the close tolerances necessary to provide a seal-tight assembly. Yet others were no less expensive than their metallic counterparts with limited, if any, benefits realized thereover.
It has, therefore, been considered desirable to produce a valve that is not only economical to manufacture but also relatively easy to operate. The valve must be durable and able to withstand extended periods of infrequent use. The various elements of the valve should be substantially immune to the deleterious effects of high pressure and corrosive action caused by interaction with the system fluid in a water heater or similar environment. Additionally, the valve must provide an effective, reliable seal and have precise on/off positions.
The subject invention is deemed to meet the foregoing needs and provide a new angle valve construction which overcomes many of the above-noted problems and others.